1. Field of the Invention
The present invention generally relates to disk driving apparatus, and more particularly, to a disk driving apparatus constructed wherein a head carriage is moved in accordance with the rotation of a lead screw.
2. Description of the Related Art
In a magnetic disk drive apparatus capable of performing magnetic reading and writing with respect to a flexible magnetic disk (hereinafter, simply referred to as a disk) accommodated in a disk cartridge, the front end of the disk cartridge comes into contact with a latch lever when the disk cartridge is inserted into a holder, so that a slider is released from engagement with the holder. The slider slides toward the front of the magnetic disk drive apparatus due to a spring force so that the holder is moved to a predetermined position, thus causing the disk accommodated in the disk cartridge to be mounted on a turntable.
Magnetic reading and writing is effected when a head carriage which supports a magnetic head is moved in a radial direction of the disk so as to allow the magnetic head to slide on the disk. One known carriage driving mechanism for moving the head carriage includes a lead screw that lies in a radial direction of the disk; a stepping motor for driving the lead screw into rotating motion; an engaging projection that is engaged with a spiral groove formed around the periphery of the lead screw; and a torsion spring which urges the lead screw toward the engaging projection.
The engaging projection engaged with the lead screw is provided to be integral with a main body of the head carriage for supporting the magnetic head. In order to reduce the weight and cost of the magnetic disk driving apparatus, the main body of the head carriage and the engaging projection are formed of a synthetic resin to be integral with each other.
In a carriage driving mechanism constructed as described above, the driving force of the lead screw that is driven into rotation is transmitted to the head carriage via the engaging projection. For this reason, the engaging projection bears a load of the head carriage.
The above-described construction of a conventional disk drive apparatus wherein the engaging projection is engaged with the spiral groove of the lead screw, the engaging projection bears a significant load when a shock is applied, causing the head carriage to undergo an excessive acceleration temporarily. Such a shock may be applied when rugged use occurs, for example, when the disk drive apparatus is carried by a user to a certain place or when an electronic equipment like a note-type personal computer having a built in disk drive apparatus, is placed on a desk.
Thus, the conventional disk drive apparatus has a problem in that the synthetic-resin engaging projection built therein may be damaged due to a shock exceeding a predetermined level is applied to the disk drive apparatus.